U.S. patent application number 10/533448 was filed with the patent office on 2006-03-02 for method and device for controlling gear shift of mechanical transmission.
This patent application is currently assigned to Mitsubishi Fuso Truck And Bus Corporation. Invention is credited to Kazunobu Eritate, Kouichi Ikeya, Toshikuni Shirasawa.
Application Number | 20060047395 10/533448 |
Document ID | / |
Family ID | 32310472 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060047395 |
Kind Code |
A1 |
Ikeya; Kouichi ; et
al. |
March 2, 2006 |
Method and device for controlling gear shift of mechanical
transmission
Abstract
Provided are a transmission control method for a mechanical
transmission, capable of shortening a gear shift time without
undergoing a shock attributed to gear disengagement, and an
apparatus therefor. The transmission control apparatus comprises
engine torque control means (S10) for controlling an engine torque
generated by an internal combustion engine so that the value of a
transfer torque of a friction clutch is 0 or near 0 when a gear
shift of the mechanical transmission is required, gear shift
allowing means (S12) for aloowing the gear shift of the mechanical
transmission when the engine torque is controlled by the engine
torque control means so that the value of the transfer torque is 0
or near 0, and gear shift executing means (S16) for disengaging and
engaging gears with the clutch kept connected when the gear shift
is allowed by the gear shift allowing means.
Inventors: |
Ikeya; Kouichi; (Tokyo,
JP) ; Eritate; Kazunobu; (Tokyo, JP) ;
Shirasawa; Toshikuni; (Tokyo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Mitsubishi Fuso Truck And Bus
Corporation
16-4, Konan 2-chome, Minato-ku
Tokyo
JP
108-8285
|
Family ID: |
32310472 |
Appl. No.: |
10/533448 |
Filed: |
November 7, 2003 |
PCT Filed: |
November 7, 2003 |
PCT NO: |
PCT/JP03/14180 |
371 Date: |
May 2, 2005 |
Current U.S.
Class: |
701/51 ;
701/56 |
Current CPC
Class: |
B60W 10/06 20130101;
F02D 2250/18 20130101; F16H 2306/50 20130101; F16H 2306/46
20130101; F02D 41/023 20130101; F16H 63/502 20130101; F02D 2250/21
20130101; F16H 61/0206 20130101; B60W 10/11 20130101; B60W 30/19
20130101; F16H 2306/42 20130101 |
Class at
Publication: |
701/051 ;
701/056 |
International
Class: |
G06F 17/00 20060101
G06F017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2002 |
JP |
2002-325386 |
Claims
1. A transmission control method for a mechanical transmission,
capable of transmitting an output of an internal combustion engine
to wheels through a friction clutch by performing automatic
multistage speed change, comprising: a step (a) of controlling an
engine torque generated by the internal combustion engine in
response to a request for a gear shift of the mechanical
transmission so that the value of a transfer torque of the friction
clutch is 0 or near 0; a step (b) of allowing the gear shift of the
mechanical transmission when the engine torque is controlled so
that the value of the transfer torque is 0 or near 0 in said step
(a); and a step (c) of disengaging and engaging gears with the
clutch kept connected when the gear shift is allowed in said step
(b).
2. A transmission control method for a mechanical transmission
according to claim 1, wherein said step (c) includes a sub-step
(c1) of changing an engine revolution speed of the internal
combustion engine after the gear disengagement is performed with
the clutch kept connected and a sub-step (c2) of performing the
gear engagement for a gear stage after the gear shift with the
clutch kept connected when the engine revolution speed is
substantially synchronous with a gear revolution speed for the gear
stage after the gear shift.
3. A transmission control method for a mechanical transmission
according to claim 1 or 2, wherein the applicable mechanical
transmission is configured so that said friction clutch can be
automatically connected and disconnected, and the step (c) includes
automatically disconnecting the friction clutch to disengage and
engage the gears if gear disengagement is not executed after a
command for gear disengagement is issued.
4. A transmission control method for a mechanical transmission
according to claim 1, wherein said step (a) includes obtaining a
changed engine torque such that the value of the transfer torque is
0 or near 0 in accordance with a first motion equation for a range
from the internal combustion engine to the friction clutch and a
second motion equation for a range from the friction clutch to each
wheel and a position on an axle shaft of a vehicle, indicating the
changed engine torque, and controlling the internal combustion
engine so that the changed engine torque is generated.
5. A transmission control method for a mechanical transmission
according to claim 4, wherein said first motion equation is
transformed on condition that an engine rotation angle acceleration
on the axle shaft is equal to an axle shaft rotation angle
acceleration on the axle shaft, and said step (a) includes
obtaining the changed engine torque in accordance with the
transformed first motion equation so that the value of the transfer
torque is 0.
6. A transmission control method for a mechanical transmission
according to claim 4, wherein said second motion equation is
transformed on condition that an engine rotation angle acceleration
on the axle shaft is equal to an axle shaft rotation angle
acceleration on the axle shaft, and said step (a) includes
obtaining the changed engine torque in accordance with the
transformed second motion equation so that the value of the
transfer torque is 0.
7. A transmission control method for a mechanical transmission
according to claim 4, wherein said friction clutch has a flywheel
and a clutch plate capable of being connected to and disconnected
from the flywheel, a motion equation for a range from the internal
combustion engine to the flywheel is used as the first motion
equation, and a motion equation for a range from the clutch plate
to each wheel and a position on the axle shaft is used as the
second motion equation.
8. A transmission control method for a mechanical transmission
according to claim 4, wherein said step (a) includes concluding
that the value of the transfer torque is 0 or near 0 after the
lapse of a predetermined period since the indication of the changed
engine torque.
9. A transmission control method for a mechanical transmission
according to claim 1, wherein said internal combustion engine
includes a fuel injection pump unit having a control rack for
adjusting a fuel injection quantity, and the step (a) includes
controlling the control rack, thereby controlling the engine
torque.
10. A transmission control method for a mechanical transmission
according to claim 9, wherein said step (b) includes determining
whether or not the value of the transfer torque is 0 or near 0
based on the position of the control rack.
11. A transmission control method for a mechanical transmission
according to claim 2, wherein said internal combustion engine has
an auxiliary brake, and said sub-step (c1) includes actuating the
auxiliary brake if the engine revolution speed of the internal
combustion engine exceeds an upper limit value of a predetermined
revolution speed range including a target engine revolution speed
corresponding to the gear revolution speed.
12. A transmission control method for a mechanical transmission
according to claim 2, wherein said sub-step (c1) includes
correcting a target engine revolution speed corresponding to the
gear revolution speed in accordance with the characteristics of the
internal combustion engine.
13. A transmission control method for a mechanical transmission
according to claim 1, wherein said step (c) includes issuing a
command to restore the engine torque after the lapse of a
predetermined period since the start of gear engagement when a gear
shift from a high-speed stage to a low-speed stage of the
mechanical transmission is required by the gear shift request.
14. A transmission control method for a mechanical transmission
according to claim 2, wherein said internal combustion engine has
an auxiliary brake, and said sub-step (c1) includes actuating the
auxiliary brake if the engine revolution speed of the internal
combustion engine exceeds an upper limit value of a predetermined
revolution speed range including a target engine revolution speed
corresponding to the gear revolution speed when a gear shift from a
low-speed stage to a high-speed stage of the mechanical
transmission is required by the gear shift request.
15. A transmission control apparatus for a mechanical transmission,
capable of transmitting an output of an internal combustion engine
to wheels through a friction clutch by performing automatic
multistage speed change, comprising: engine torque control means
for controlling an engine torque generated by the internal
combustion engine so that the value of a transfer torque of the
friction clutch is 0 or near 0 when a gear shift of the mechanical
transmission is required; gear shift allowing means for allowing
the gear shift of the mechanical transmission when the engine
torque is controlled by the engine torque control means so that the
value of the transfer torque is 0 or near 0; and gear shift
executing means for disengaging and engaging gears with the clutch
kept connected when the gear shift is allowed by the gear shift
allowing means.
16. A transmission control apparatus for a mechanical transmission
according to claim 15, which further comprises engine revolution
speed detecting means for detecting an engine revolution speed of
the internal combustion engine and gear revolution speed detecting
means for detecting a gear revolution speed for a gear stage after
the gear shift, and wherein said gear shift executing means changes
the engine revolution speed of the internal combustion engine after
the gear disengagement is performed with the clutch kept connected
and performs the gear engagement for the gear stage after the gear
shift with the clutch kept connected when the engine revolution
speed is substantially synchronous with the gear revolution speed
for the gear stage after the gear shift.
17. A transmission control apparatus for a mechanical transmission
according to claim 15 or 16, wherein said friction clutch is
configured to be able to be automatically connected and
disconnected, and the gear shift executing means automatically
disconnects the friction clutch to disengage and engage the gears
if gear disengagement is not executed after a command for gear
disengagement is issued.
18. A transmission control apparatus for a mechanical transmission
according to claim 15, wherein said friction clutch has a flywheel
and a clutch plate capable of being connected to and disconnected
from the flywheel, and said engine torque control means obtains a
changed engine torque such that the value of the transfer torque is
0 or near 0 in accordance with a first motion equation for a range
from the internal combustion engine to the flywheel and a second
motion equation for a range from the friction clutch to each wheel
and a position on an axle shaft of a vehicle and controls the
internal combustion engine so that the changed engine torque is
generated.
19. A transmission control apparatus for a mechanical transmission
according to claim 15, wherein said internal combustion engine
includes a fuel injection pump unit having a control rack for
adjusting a fuel injection quantity, and said engine torque control
means controls the control rack, thereby controlling the engine
torque.
20. A transmission control apparatus for a mechanical transmission
according to claim 16, wherein said internal combustion engine has
an auxiliary brake, and said gear shift executing means actuates
the auxiliary brake if the engine revolution speed of the internal
combustion engine exceeds an upper limit value of a predetermined
revolution speed range including a target engine revolution speed
corresponding to the gear revolution speed.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method and an apparatus
for transmission control for a mechanical transmission, and more
specifically, to a technique for performing a gear shift without
connecting or disconnecting a friction clutch.
BACKGROUND ART
[0002] Transmissions of which gear shift operation is automated are
frequently used as vehicular transmissions. In large vehicles, such
as buses, trucks, etc., the transfer amount of driving torque is so
large that it is hard for a torque converter to transfer the
driving torque satisfactorily. For example, a mechanical
transmission, which is designed so that gear shift operation for a
manual mechanical transmission is automated, is employed.
[0003] This mechanical transmission is configured to achieve a gear
shift by automatically carrying out gear engagement and gear
disengagement. As for a friction clutch, it is configured to be
automatically connected and disconnected in accordance with the
gear shift or a stop of the vehicle.
[0004] In automatically controlling the friction clutch in
accordance with the gear shift in the mechanical transmission,
however, delicate control in a half-clutched state is difficult.
Therefore, the time during which the friction clutch is
disconnected so that no driving force can be transmitted to wheels
is long, and the period of execution of the gear shift may be felt
long.
[0005] On the other hand, a technique is devised so that fuel
supply to an internal combustion engine is repeatedly adjusted as a
dog clutch of the transmission is disengaged, whereby a transfer
torque is cut off so that the dog clutch can be disengaged
satisfactorily (e.g., see Japanese Patent Publication No. 1-164633
(Japanese Patent No. 2887481), hereinafter referred to as patent
document 1).
[0006] In consideration of the patent document 1 described above, a
gear shift can be achieved without disconnecting the friction
clutch in the mechanical transmission.
[0007] According to the foregoing patent document 1, however, the
dog clutch is urged to be disengaged as the fuel supply to the
internal combustion engine is adjusted, and the point of time when
the dog clutch is disengaged, i.e. the time of gear disengagement
is not clear. In other words, the timing for the gear disengagement
is not fixed according to the patent document 1. Therefore, it can
be supposed that, depending on the engine torque of the internal
combustion engine varying with the increase or decrease of the fuel
supply, the gear disengagement is performed inevitably even if the
transfer torque is not fully cut off, in many cases.
[0008] If the gear disengagement is performed in this manner
without fully cutting off the transfer torque, and if the transfer
torque is relatively high, a shock is generated by the gear
disengagement, unfavorably giving a feeling of wrongness to
occupants of the vehicle.
DISCLOSURE OF THE INVENTION
[0009] The present invention has been made in order to solve these
problems, and its object is to provide a transmission control
method for a mechanical transmission, capable of shortening a gear
shift time without undergoing a shock attributed to gear
disengagement, and an apparatus therefor.
[0010] In order to achieve the above object, according to the
present invention, a transmission control method for a mechanical
transmission, capable of transmitting an output of an internal
combustion engine to wheels through a friction clutch by performing
automatic multistage speed change, comprises a step (a) of
controlling an engine torque generated by the internal combustion
engine in response to a request for a gear shift of the mechanical
transmission so that the value of a transfer torque of the friction
clutch is 0 or near 0, a step (b) of allowing the gear shift of the
mechanical transmission when the engine torque is controlled so
that the value of the transfer torque is 0 or near 0 in the step
(a), and a step (c) of disengaging and engaging gears with the
clutch kept connected when the gear shift is allowed in the step
(b).
[0011] According to the transmission control method of the present
invention, the engine torque is controlled in response to the
request for a gear shift. If the value of the transfer torque of
the friction clutch is 0 or near 0, therefore, the gears are
disengaged and engaged with the clutch kept connected, so that the
gear shift can be achieved in a short time without undergoing a
shock attributed to the gear disengagement.
[0012] In the present invention, the step (c) may include a
sub-step (c1) of changing an engine revolution speed of the
internal combustion engine after the gear disengagement is
performed with the clutch kept connected and a sub-step (c2) of
performing the gear engagement for a gear stage after the gear
shift with the clutch kept connected when the engine revolution
speed is substantially synchronous with a gear revolution speed for
the gear stage after the gear shift. When the gear disengagement is
performed, in this preferred aspect, the engine revolution speed is
changed to be synchronous with the gear revolution speed for the
gear stage after the gear shift, so that the gear engagement can be
carried out smoothly with no rotational speed difference without
connecting or disconnecting the clutch.
[0013] In the transmission control method of the present invention,
moreover, the applicable mechanical transmission is configured so
that the friction clutch can be automatically connected and
disconnected, and the step (c) may include automatically
disconnecting the friction clutch to disengage and engage the gears
if gear disengagement is not executed after a command for gear
disengagement is issued. If the gear disengagement fails to be
executed despite the issuance of the command for gear
disengagement, in this preferred aspect, the gear disengagement and
gear engagement can be performed securely with the friction clutch
disconnected, and the gear shift can be executed securely.
[0014] In the transmission control method of the present invention,
the step (a) may include obtaining a changed engine torque such
that the value of the transfer torque is 0 or near 0 in accordance
with a first motion equation for a range from the internal
combustion engine to the friction clutch and a second motion
equation for a range from the friction clutch to each wheel and a
position on an axle shaft of a vehicle, indicating the changed
engine torque, and controlling the internal combustion engine so
that the changed engine torque is generated. Further, the first or
second motion equations are transformed on condition that an engine
rotation angle acceleration on the axle shaft is equal to an axle
shaft rotation angle acceleration on the axle shaft, and the step
(a) may include obtaining the changed engine torque in accordance
with the transformed first or second motion equation so that the
value of the transfer torque is 0. In a preferred aspect such that
the friction clutch has a flywheel and a clutch plate capable of
being connected to and disconnected from the flywheel, a motion
equation for a range from the internal combustion engine to the
flywheel may be used as the first motion equation, and a motion
equation for a range from the clutch plate to each wheel and a
position on the axle shaft may be used as the second motion
equation.
[0015] Moreover, the step (a) may include concluding that the value
of the transfer torque is 0 or near 0 after the lapse of a
predetermined period since the indication of the changed engine
torque.
[0016] The internal combustion engine may include a fuel injection
pump unit having a control rack for adjusting a fuel injection
quantity. In this preferred aspect, the step (a) may include
controlling the control rack, thereby controlling the engine
torque, and the step (b) may include determining whether or not the
value of the transfer torque is 0 or near 0 based on the position
of the control rack.
[0017] The internal combustion engine may have an auxiliary brake.
In this preferred aspect, the sub-step (c1) may include actuating
the auxiliary brake if the engine revolution speed of the internal
combustion engine exceeds an upper limit value of a predetermined
revolution speed range including a target engine revolution speed
corresponding to the gear revolution speed.
[0018] Moreover, the sub-step (c1) may include correcting a target
engine revolution speed corresponding to the gear revolution speed
in accordance with the characteristics of the internal combustion
engine.
[0019] Furthermore, the step (c) may include issuing a command to
restore the engine torque after the lapse of a predetermined period
since the start of gear engagement, when a gear shift from a
high-speed stage to a low-speed stage of the mechanical
transmission is required by the gear shift request.
[0020] In order to achieve the above object, a transmission control
apparatus for a mechanical transmission according to the present
invention, capable of transmitting an output of an internal
combustion engine to wheels through a friction clutch by performing
automatic multistage speed change, comprises engine torque control
means for controlling an engine torque generated by the internal
combustion engine so that the value of a transfer torque of the
friction clutch is 0 or near 0 when a gear shift of the mechanical
transmission is required, gear shift allowing means for allowing
the gear shift of the mechanical transmission when the engine
torque is controlled by the engine torque control means so that the
value of the transfer torque is 0 or near 0, and gear shift
executing means for disengaging and engaging gears with the clutch
kept connected when the gear shift is allowed by the gear shift
allowing means.
[0021] When the gear shift of the mechanical transmission is
required, therefore, the engine torque generated by the internal
combustion engine is controlled by the engine torque control means
so that the value of the transfer torque is 0 or near 0. If the
value of the transfer torque reaches 0 or near 0, the gear shift is
allowed by the gear shift allowing means, and the gear
disengagement and gear engagement are performed with the clutch
kept connected by the gear shift executing means.
[0022] Thus, when the value of the transfer torque securely reaches
0 or near 0, the gear disengagement can be performed without
connecting or disconnecting the clutch, and therefore, the gear
shift time can be shortened so that the gear shift can be quickly
achieved without undergoing a shock attributed to the gear
disengagement.
[0023] Moreover, the transmission control apparatus for a
mechanical transmission according to the present invention may
further comprise engine revolution speed detecting means for
detecting an engine revolution speed of the internal combustion
engine and gear revolution speed detecting means for detecting a
gear revolution speed for a gear stage after the gear shift. In
this preferred aspect, the gear shift executing means changes the
engine revolution speed of the internal combustion engine after the
gear disengagement is performed with the clutch kept connected and
performs the gear engagement for the gear stage after the gear
shift with the clutch kept connected when the engine revolution
speed is substantially synchronous with the gear revolution speed
for the gear stage after the gear shift.
[0024] When the gear disengagement is performed, in the preferred
aspect described above, the engine revolution speed of the internal
combustion engine is changed to be synchronous with the gear
revolution speed for the gear stage after the gear shift, so that
the gear engagement can be carried out smoothly with no rotational
speed difference without connecting or disconnecting the
clutch.
[0025] In the transmission control apparatus for a mechanical
transmission according to the present invention, furthermore, the
friction clutch may be configured to be able to be automatically
connected and disconnected. In this preferred aspect, the gear
shift executing means automatically disconnects the friction clutch
to disengage and engage the gears if gear disengagement is not
executed after a command for gear disengagement is issued.
[0026] If the gear disengagement fails to be executed despite the
issuance of the command for gear disengagement by the gear shift
executing means, in the preferred aspect described above, the gear
disengagement and gear engagement can be performed securely with
the friction clutch disconnected, and the gear shift can be
executed securely.
[0027] In the transmission control apparatus of the present
invention, the friction clutch may have a flywheel and a clutch
plate capable of being connected to and disconnected from the
flywheel. In this preferred aspect, the engine torque control means
can obtain a changed engine torque such that the value of the
transfer torque is 0 or near 0 in accordance with a first motion
equation for a range from the internal combustion engine to the
flywheel and a second motion equation for a range from the friction
clutch to each wheel and a position on an axle shaft of a vehicle
and control the internal combustion engine so that the changed
engine is generated.
[0028] Further, the internal combustion engine may include a fuel
injection pump unit having a control rack for adjusting a fuel
injection quantity. In this preferred aspect, the engine torque
control means can control the control rack, thereby controlling the
engine torque.
[0029] Furthermore, the internal combustion engine may have an
auxiliary brake. In this preferred aspect, the gear shift executing
means actuates the auxiliary brake if the engine revolution speed
of the internal combustion engine exceeds an upper limit value of a
predetermined revolution speed range including a target engine
revolution speed corresponding to the gear revolution speed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic diagram of a drive system of a vehicle
(bus or the like) to which a transmission control apparatus for a
mechanical transmission according to the present invention is
applied;
[0031] FIG. 2 is a part of a flowchart showing a control routine of
clutchless shift control according to a first embodiment of the
present invention;
[0032] FIG. 3 is the remainder of the flowchart continued from FIG.
2, showing the control routine of the clutchless shift control
according to the present invention;
[0033] FIG. 4 is a flowchart showing a control routine of Ne-F/B
control of FIG. 2;
[0034] FIG. 5 is the remainder of the flowchart continued from FIG.
3, showing the control routine of the clutchless shift control
according to the present invention; and
[0035] FIG. 6 is a part of a flowchart showing a control routine of
clutchless shift control according to a second embodiment of the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0036] An embodiment of the present invention will now be described
with reference to the drawings.
[0037] FIG. 1 shows an outline of a drive system of a vehicle (bus
or the like) to which a transmission control apparatus for a
mechanical transmission according to the present invention is
applied. Referring now to FIG. 1, there will be described a
configuration of the drive system of the vehicle that includes the
transmission control apparatus for the mechanical transmission
according to the present invention.
[0038] As shown in the figure above, a diesel engine (hereinafter
referred to as engine) 1 is provided with a fuel injection pump
unit (hereinafter referred to as injection pump) 6 for supplying a
fuel. The injection pump 6 is a device that injects the fuel by
actuating a pump with an output of the engine 1 transmitted through
a pump input shaft (not shown). The injection pump 6 is provided
with a control rack (not shown) for adjusting the fuel injection
quantity and a rack position sensor 9 for detecting a rack position
(control rack position) SRC of the control rack. Further, an engine
revolution speed sensor (engine revolution speed detecting means) 8
for detecting the rotational frequency of the pump input shaft and
detecting the rotational frequency of an engine output shaft 2,
that is, an engine revolution speed Ne, in accordance with the
foregoing rotational frequency is attached near the pump input
shaft.
[0039] The engine output shaft 2 extends from the engine 1. This
engine output shaft 2 is connected to an input shaft 20 of a gear
transmission (hereinafter referred to as transmission) through a
clutch unit 3. Thus, the output of the engine 1 is transmitted to
the transmission 4, whereupon a speed change is executed in the
transmission 4. The transmission 4 is a mechanical transmission
that has, for example, five forward gear change stages (first to
fifth gear change stages), besides a reverse gear stage, and can
perform a manual gear shift as well as an automatic gear shift. The
clutch unit 3 is constructed so that the transmission 4 can be
automatically controlled to be connected to and disconnected from
the engine 1 when the vehicle is stopped or started. In some cases,
the clutch unit 3 may be automatically controlled for connection
and disconnection at the time of an automatic gear shift, as
described after.
[0040] The clutch unit 3 enables automatic execution of operation
of a conventional mechanical-friction clutch such that a connected
state is established by pressing a clutch plate 12 against a
flywheel 10 by means of a pressure spring 11 or that a disconnected
state is established by separating the clutch plate 12 from the
flywheel 10. The clutch plate 12 can be automatically operated by a
clutch actuator for clutch connection and disconnection, that is, a
clutch actuator 16, aided by an outer lever 12a.
[0041] More specifically, the clutch actuator 16 is connected with
an air tank 34 by an air passage 30 as an air supply passage. Thus,
when operation air from the air tank 34 is supplied through the air
passage 30, the clutch actuator 16 is actuated automatically.
Thereupon, the clutch plate 12 moves, and the clutch unit 3 is
connected or disconnected automatically.
[0042] Actually, the air passage 30 is fitted with an
electropneumatic proportional control valve 31, which is driven, in
response to a signal from an electronic control unit (ECU) 80, to
allow and cut off circulation of the operation air. If a drive
signal is supplied from the ECU 80 to the electropneumatic
proportional control valve 31, the operation air is supplied from
the air tank 34 to the clutch actuator 16 through the
electropneumatic proportional control valve 31, whereupon the
clutch actuator 16 is actuated to disconnect the clutch unit 3. If
the supply of the drive signal is stopped, on the other hand, the
operation air supply from the air tank 34 to the clutch actuator 16
is interrupted, and the working air in the clutch actuator 16 is
discharged into the atmosphere. Thereupon, the clutch unit 3 is
connected by the agency of the pressure spring 11.
[0043] The clutch actuator 16 is fitted with a clutch stroke sensor
17 that detects a movement of the clutch plate 12, i.e. a clutch
stroke.
[0044] A change lever 60 is a select lever of the transmission 4
and is provided with an N (neutral) range, R (reverse) range, and D
(drive) range that corresponds to an automatic gear shift mode.
[0045] The change lever 60 is provided with a select position
sensor 62 that detects each range position. This select position
sensor 62 is connected to the ECU 80. On the other hand, the ECU 80
is connected to a gear shift unit 64 for switching the engagement
of gears of the transmission 4, that is, a gear position. When a
position signal is supplied from the select position sensor 62 to
the ECU 80, therefore, a drive signal is delivered from the ECU 80
to the gear shift unit 64 in response to the position signal.
Thereupon, the gear shift unit 64 is actuated to shift the gear
position of the transmission 4 to a selected desired select range.
If the select position is in the D range, automatic transmission
control is executed depending on the driving state of the vehicle,
which will be described in detail later, and the gear position is
shifted under this automatic transmission control.
[0046] The gear shift unit 64 includes a solenoid valve 66, which
is actuated by an operation signal from the ECU 80, and a power
cylinder (not shown) that actuates a shift fork (not shown) in the
transmission 4. The power cylinder is connected to the air passage
30 through the solenoid valve 66 and an air passage 67. Thus, when
the operation signal from the ECU 80 is applied to the solenoid
valve 66, the solenoid valve 66 is opened or closed in response to
the operation signal, and the power cylinder is actuated by the
operation air supply from the air tank 34. Thereupon, the
engagement of the gear of the transmission 4 is suitably changed
by, for example, a racing gear. Only one solenoid valve 66 is
illustrated in this case. Actually, however, a plurality of shift
forks are arranged, a plurality of power cylinders are provided
corresponding to the shift forks, and a plurality of solenoid
valves 66 are provided corresponding to the power cylinders.
[0047] A gear position sensor 68 for detecting each gear stage is
attached near the gear shift unit 64 of the transmission 4 and
connected electrically to the ECU 80. A current gear position
signal, i.b. gear stage signal is delivered from the gear position
sensor 68 to the ECU 80.
[0048] An accelerator pedal 70 is provided with an accelerator
opening sensor 72 and also connected electrically to the ECU 80. An
amount of depression of the accelerator pedal 70, that is,
accelerator opening information .theta.acc, is outputted from the
accelerator opening sensor 72.
[0049] Further, an output shaft 76 of the transmission 4 is
provided with a revolution speed sensor 78 that detects and outputs
the revolution speed of the output shaft 76, and this revolution
speed sensor 78 is also connected electrically to the ECU 80. A
vehicle speed V is calculated in the ECU 80 in accordance with
information from the revolution speed sensor 78.
[0050] In FIG. 1, numeral 82 denotes an engine control unit 82 that
is provided independently of the ECU 80. The engine control unit 82
is a device that supplies an electronic governor (not shown) in the
injection pump 6 with a signal from the ECU 80, corresponding to
information from each sensor, the accelerator opening information
.theta.acc, etc., and controls the drive of the engine 1. More
specifically, if a command signal is supplied from the engine
control unit 82 to the electronic governor, the control rack is
actuated to carry out fuel increasing or decreasing operation, and
the increase or decrease of an engine torque Te or the engine
revolution speed Ne is controlled. Detection information from the
rack position sensor 9 and the engine revolution speed sensor 8 is
supplied to the ECU 80 through the engine control unit 82.
[0051] Further, an exhaust pipe 50 extending from an exhaust
manifold 7 of the engine 1 is provided with an exhaust brake 52.
The exhaust brake 52, which is composed of a butterfly valve 54, is
connected to the ECU 80 and configured to be able to adjust the
exhaust flow rate by closing the butterfly valve 54 in response to
a command from the ECU 80. Thus, the engine output and the engine
revolution speed Ne are reduced, so that a braking force is applied
to the vehicle.
[0052] The ECU 80 is composed of a microcomputer (CPU), a memory,
interfaces for input/output signal processing, etc. As mentioned
before, an input-side interface of the ECU 80 are connected with
the clutch stroke sensor 17, select position sensor 62, gear
position sensor 68, accelerator opening sensor 72, revolution speed
sensor 78, engine control unit 82, etc.
[0053] On the other hand, an output-side interface of the ECU 80 is
connected with a warning lamp 83, as well as the solenoid valve 66,
engine control unit 82, clutch actuator 16, exhaust brake 52, etc.
mentioned before.
[0054] The following is a description of transmission control of
the transmission control apparatus for the mechanical transmission
according to the present invention constructed in this manner.
[0055] A first embodiment will be described first.
[0056] Referring now to FIGS. 2 to 5, there is shown a flow chart
for control routines of clutchless shift control according to the
present invention, and the following description is based on this
flowchart.
[0057] In Step S10 of FIG. 2, a command is issued to change the
engine torque Te (engine torque control means) in response to a
gear shift command from the ECU 80. More specifically, in doing
this, the engine 1 is controlled to change the engine torque Te so
that the value of a transfer torque of the clutch unit 3, i.e. a
clutch torque Tcl between the flywheel 10 and the clutch plate 12,
is 0 or near 0.
[0058] More specifically, the engine torque Te to be changed is
obtained as follows so that the value of the clutch torque Tcl is,
for example, 0, according to a motion equation (equation (1)) for a
range from the engine 1 to the flywheel 10 and a motion equation
(equation (2)) for a range from the clutch plate 12 to each wheel
and a position on an axle shaft of the vehicle: ( Te - Tcl ) it if
= Ie it 2 if 2 d 2 .times. .theta. .times. .times. e / d t 2 , ( 1
) Tcl it if - ( W .function. ( .mu. + sin .times. .times. .theta. )
+ .lamda. .times. .times. AV 2 ) .times. R .times. .times. .eta. =
( W / g R 2 + ( Iw + ( If + It it 2 ) if 2 ) ) d 2 .times. .times.
.theta. .times. .times. ax / dt 2 . ( 2 ) ##EQU1##
[0059] The parameters are: [0060] g: gravitational acceleration,
[0061] .eta.: power transfer efficiency, [0062] .mu.: rolling
resistance coefficient, [0063] .lamda.: air resistance coefficient,
[0064] Ie: moment of inertia of rotating portion of engine input
shaft [0065] It: moment of inertia of transmission [0066] If:
moment of inertia of rotating portion of differential gear input
shaft [0067] Iw: moment of inertia of axle and same rotating
portion [0068] it: transmission gear ratio [0069] if: differential
gear ratio [0070] W: vehicle weight [0071] A: front projection area
[0072] R: wheel radius [0073] Te: engine torque (on input shaft of
transmission) [0074] Tcl: clutch torque (on input shaft of
transmission) [0075] V: vehicle speed [0076]
d.sup.2.theta.e/dt.sup.2: engine rotation angular acceleration (on
axle shaft) [0077] d.sup.2.theta.ax/dt.sup.2: axle shaft rotation
angular acceleration (on axle shaft)
[0078] If the value of the clutch torque Tcl is adjusted to, for
example, 0, in this case,
d.sup.2.theta.e/dt.sup.2=d.sup.2.theta.ax/dt.sup.2 is obtained, so
that the equations (1) and (2) can be transformed into equations
(3) and (4) as follows: Teitif=I1d.sup.2.theta.e/dt.sup.2, (3)
-(W(.mu.+sin
.theta.)+.lamda.AV.sup.2)R.eta.=(I2+I3)d.sup.2.theta.e/dt.sup.2.
(4)
[0079] Here I1, I2 and I3 are I1=Ieit.sup.2if.sup.2 (inertia of
engine), I2=(Iw+(If+Itit.sup.2)if.sup.2) (inertia of rotating
portion), and I3=W/gR.sup.2 (inertia corresponding to vehicle
weight), respectively.
[0080] Thus, if d.sup.2.theta.e/dt.sup.2 is eliminated, the engine
torque Te can be obtained according to the following equation (5):
Te=(-(W(.mu.+sin .theta.)+.lamda.AV.sup.2)R.eta./(itif))I1(I2+I3).
(5)
[0081] If the engine torque Te is given in this manner, the control
rack is controlled so that the engine torque Te can be obtained,
whereby the fuel injection quantity is changed.
[0082] In the following Step S12, it is determined whether or not
the value of the clutch torque Tcl is 0 (zero) or near 0. Here it
is determined whether or not the actual engine torque Te is
substantially equal to the engine torque Te that is obtained from
the equation (5). More specifically, it is determined whether or
not a desired rack position is reached by the rack position SRC in
accordance with the information from the rack position sensor 9.
Alternatively, a torque sensor may be provided to directly detect
that the value of the clutch torque Tcl is 0 (zero) or near 0.
[0083] The program proceeds to Step S16 (gear shift allowing means)
if the decision in Step S12 is positive (Yes), that is, if it is
concluded that the desired rack position is reached by the rack
position SRC and that the value of the clutch torque Tcl is 0 or
near 0. On the other hand, the program proceeds to Step S14 to
continue changing the fuel injection quantity until a predetermined
period t1 elapses after the issuance of the command to change the
engine torque Te if the decision in Step S12 is negative (No), that
is, if it is concluded that the desired rack position is not
reached by the rack position SRC and that the value of the clutch
torque Tcl is not yet 0 or near 0.
[0084] In Step S14, the predetermined period t1 is a time
corresponding to a response delay of the control rack, for example.
If the predetermined period t1 is found to have elapsed, the value
of the clutch torque Tcl can be regarded to have reached 0 or near
0. Thus, if the decision in Step S14 is positive (Yes), that is, if
the predetermined period t1 is concluded to have elapsed, the
program proceeds to Step S16 in the same manner as aforesaid.
[0085] In Step S16, a command is issued to disengage the gears of
the transmission 4 (gear shift executing means). If the value of
the clutch torque Tcl is 0 or near 0, as mentioned before, no
transfer torque is produced between the flywheel 10 and the clutch
plate 12 or between the gears of the transmission 4, so that the
gears should be able to be easily disengaged without any shock
although the clutch unit 3 is not disconnected. Thus, in this case,
the gears are disengaged by means of the gear shift unit 64 with
the flywheel 10 and the clutch plate 12 kept connected to each
other without disconnecting the clutch unit 3.
[0086] In Step S18, it is determined whether or not the gears are
disengaged. In this case, it is determined whether or not the gears
are disengaged to establish a neutral state in the transmission 4
in accordance with information from the gear position sensor 68. If
the decision is negative (No), that is, if it is concluded that the
gears are not disengaged, the program proceeds to Step S30 of FIG.
3.
[0087] In Step S30, it is determined whether or not a predetermined
period t3 has elapsed since the issuance of the command to
disengage the gears. The predetermined period t3 is a time that
exceeds a response delay of the shift fork, for example. Normally,
the gears should be disengaged before the lapse of the
predetermined period t3. If the decision is negative (No), that is,
before the lapse of the predetermined period t3, therefore, the
determination of Step S18 is continued to wait the disengagement of
the gears.
[0088] If the decision in Step S30 is positive (Yes), that is, if
the predetermined period t3 is concluded to have elapsed, on the
other hand, the gears may be supposed to be unreleasable with the
clutch unit 3 left connected, for some reason. This may, for
example, be a situation where the parameters in the equation (5)
are so inaccurate that the engine torque Te cannot be obtained
correctly or a situation where the rack position sensor 9 has a
failure. In this case, therefore, the program proceeds to Step S32,
in which the clutch actuator 16 is actuated to automatically
disconnect the clutch unit 3 (automatic declutching), and the
program proceeds to Step S34.
[0089] In Step S34, it is determined whether or not a predetermined
period t4 has elapsed since the automatic disconnection of the
clutch unit 3. The predetermined period t4 is a time that exceeds a
response delay of the clutch actuator 16, for example. Normally,
the clutch unit 3 should be disconnected to allow the gears to be
disengaged before the lapse of the predetermined period t4. If the
decision is negative (No), that is, before the lapse of the
predetermined period t4, therefore, the determination of Step S18
is continued to wait the disengagement of the gears.
[0090] If the decision in Step S34 is positive (Yes), that is, if
the predetermined period t4 is concluded to have elapsed, on the
other hand, the gear disengagement itself may be supposed to be
unattainable for some reason. In this case, therefore, the
transmission 4 is concluded to be out of order, whereupon the
program proceeds to Step S36, in which the entire automatic
transmission control is stopped, and the warning lamp 83 is turned
on to inform a driver of the trouble.
[0091] If the decision in Step S18 is positive (Yes), that is, if
the gears are concluded to have been disengaged, the program
proceeds to Step S20.
[0092] In Step S20, it is determined whether or not the clutch unit
3 is disconnected automatically. If the decision is negative (No),
that is, if the clutch unit 3 is not disconnected automatically,
the program proceeds to Step S24. If the clutch unit 3 is
disconnected automatically in the aforesaid manner, on the other
hand, the decision is positive (Yes). In this case, the program
proceeds to Step S24 after the clutch unit 3 is connected in Step
S22.
[0093] In Step S24, the lapse of the predetermined period t2 is
awaited. In Step S26, thereafter, feedback control (Ne-F/B control)
of the engine revolution speed Ne is carried out in Step S26. In
this Ne-F/B control, as shown in the subroutine in FIG. 4, the
engine revolution speed Ne is substantially synchronized with a
gear revolution speed for a gear stage after the gear shift.
[0094] In the Ne-F/B control, it is determined whether or not the
time that has elapsed since the start of the NE-F/B control is
within a predetermined period t5 in Step S40. Immediately after the
start of the Ne-F/B control, the decision is positive (Yes), so
that the program proceeds to Step S42.
[0095] In Step S42, it is determined whether or not the engine
revolution speed Ne is near the gear revolution speed for the gear
stage after the gear shift, that is, a target Ne (Ne=target
Ne.+-.N1). The gear revolution speed for the gear stage after the
gear shift, that is, the target Ne, can be easily calculated from
the revolution speed of the output shaft 76, which is detected by
the revolution speed sensor 78, and the gear ratio (gear revolution
speed detecting means). If the decision is negative (No), that is,
if it is concluded that the engine revolution speed Ne is not equal
to or near the target Ne after the gear shift, the program proceeds
to Step S44.
[0096] In Step S44, it is determined whether or not the engine
revolution speed Ne is within a revolution speed range such that it
is higher than the target Ne after the gear shift by a
predetermined value N2 (Ne.ltoreq.target Ne+N2). If the decision is
negative (No), the engine revolution speed Ne can be concluded to
be too high. In this case, the program proceeds to Step S46, in
which an auxiliary brake is turned on. More specifically, the
exhaust brake 52 is closed to lower the engine revolution speed
Ne.
[0097] If the decision in Step S44 is positive (Yes), on the other
hand, the engine revolution speed Ne can be concluded to be not so
high. In this case, the program proceeds to Step S48, in which the
auxiliary brake is turned off, and the program proceeds to Step
S50.
[0098] If the target Ne is directly given as a command to the
engine 1 for control such that the engine revolution speed Ne is
adjusted to the target Ne, it takes time for the engine revolution
speed Ne to reach the target Ne or a deviation may be left between
the engine revolution speed Ne and the target Ne, depending on the
engine characteristics. In Step S50, therefore, a command is issued
to correct the target Ne, and the engine is controlled so that the
corrected target Ne is obtained. Thus, the engine revolution speed
Ne can be controlled to be equal to the target Ne without a
deviation in a short time.
[0099] If the decision in Step S42 is positive (Yes), that is, if
it is concluded that the engine revolution speed Ne is equal to or
near the target Ne after the gear shift or that the engine
revolution speed Ne is substantially synchronous with the target Ne
for the gear stage after the gear shift, on the other hand, the
program proceeds to Step S52, in which the auxiliary brake is
turned off. In Step S54, it is determined whether or not a
predetermined period t6 has elapsed since the start of the Ne-F/B
control.
[0100] If the decision in Step S54 is negative (No), that is,
before the lapse of the predetermined period t6, a command for the
target Ne is issued in Step S56. If the decision is positive (Yes),
that is, after the lapse of the predetermined period t6, or if the
decision in Step S40 is negative (No), that is, after the lapse of
the predetermined period t5, the Ne-F/B control is terminated, and
the program proceeds to Step S28 of FIG. 2.
[0101] In Step S28, the auxiliary brake is turned off again, and
the program proceeds to Step S60 of FIG. 5.
[0102] In Step S60, a command for gear shift (gear engagement) is
issued, based on the conclusion that the engine revolution speed Ne
is equal to or near the target Ne for the gear stage after the gear
shift. If the engine revolution speed Ne is substantially
synchronous with the target Ne for the gear stage after the gear
shift, the gears should be able to engage smoothly without
disconnection of the clutch unit 3. In this case, therefore, the
gear shift (gear engagement) is performed with the gear shift unit
64 without disconnecting the clutch unit 3, that is, without
disconnecting the flywheel 10 and the clutch plate 12 from each
other.
[0103] In Step S62, it is determined whether or not the gear shift
is completed. Based on the information from the gear position
sensor 68, in this case, it is determined whether or not the gear
shift is achieved so that the gear stage is switched over to a gear
stage after the gear shift. If the decision is negative (No), that
is, if it is concluded that the gear shift is not achieved, the
program proceeds to Step S64, in which a command for gear shift is
issued. Thereafter, it is determined whether or not a predetermined
period t7 has elapsed. The predetermined period t7, like the
predetermined period t3, is a time that exceeds the response delay
of the shift fork, for example. Normally, the gears should be
engaged before the lapse of the predetermined period t7. If the
decision is negative (No), that is, before the lapse of the
predetermined period t7, therefore, the determination of Step S62
is continued to wait the engagement of the gears.
[0104] If the decision in Step S64 is positive (Yes), that is, if
the predetermined period t7 is concluded to have elapsed, on the
other hand, the gear shift itself may be supposed to be
unattainable for some reason. In this case, therefore, the
transmission 4 is concluded to be out of order, whereupon the
program proceeds to Step S66, in which the issuance of the command
for shift is stopped, and the warning lamp 83 is turned on to
inform the driver of the trouble.
[0105] If the decision in Step S62 is positive (Yes), that is, if
the gear shift is concluded to have been completed, the program
proceeds to Step S68.
[0106] In Step S68, it is determined whether or not a predetermined
period t8 has elapsed in the case of shift-down. If the decision is
negative (No), the lapse of the predetermined period t8 is awaited.
If the decision is positive (Yes), on the other hand, the program
proceeds to Step S70.
[0107] In Step S70, the warning lamp 83 is kept off with the gear
shift is performed without problems and completed. Then, in
following Step S72, a command is issued to restore the engine
torque Te, having been changed in Step S10, in response to the
completion of the gear shift, and the engine control is returned to
a normal control state to restore the engine torque Te.
[0108] In the case of the shift-down (shift-down in a state where
an accelerator is not depressed and other than a kick-down shift),
the engine torque Te is increased to raise the engine revolution
speed Ne. If the command is issued to restore the engine torque Te
immediately after the gear shift (gear engagement) is performed in
this state, the engine torque increase control is stopped to cause
the engine torque Te to change suddenly, so that the gears may
possibly be disengaged. In the case of the shift-down, therefore,
it is determined whether or not the predetermined period t8 has
elapsed in Step S68. If the decision is positive (Yes), that is,
after the lapse of the predetermined period t8, the command to
restore the engine torque Te is issued in Step S72 following Step
S70. Thus, the engine torque Te is restrained from changing
suddenly, so that gear disengagement is prevented.
[0109] In the case of shift-up, moreover, the engine revolution
speed Ne is reduced, so that the engine torque Te never increases.
Therefore, the gears can never be disengaged even if the engine
torque Te is restored immediately after the gear shift (gear
engagement) is performed. Thus, in the case of shift-up, the
program proceeds to Step S72 without awaiting the lapse of the
predetermined period t8, whereupon the command is issued at once to
restore the engine torque Te.
[0110] A series of clutchless shift control operations is finished
in this manner.
[0111] The following is a description of a second embodiment.
[0112] Referring to FIG. 6, there is shown a flowchart illustrating
a control routine of clutchless shift control according to the
second embodiment of the present invention. The second embodiment
will now be described with reference to this flowchart. Same step
numbers are used to designate the same portions as those of the
first embodiment, and a description of those portions will be
omitted. Only those portions which are different from the
counterparts of the first embodiment will be described in the
following.
[0113] In Step S12' following Step S10, it is determined whether or
not a predetermined period t0 has elapsed since the change of the
engine torque Te based on a gear shift command. More specifically,
the engine torque Te is obtained, and the fuel injection quantity
is changed by controlling the control rack so that the engine
torque Te can be obtained. If the predetermined period to elapses
thereafter, the value of the clutch torque Tcl can be concluded to
have reached 0 (zero) or near 0. If the decision is positive (Yes),
that is, if the predetermined period t0 is concluded to have
elapsed, the program proceeds to Step S16, in which the command for
gear disengagement is issued. Also in this case, the gears should
be able to be easily disengaged without shock even though the
clutch unit 3 is not disconnected.
[0114] If the decision in Step S12' is negative (No), that is, if
the predetermined period to is not concluded to have elapsed, on
the other hand, the lapse of the predetermined period t0 is
awaited.
[0115] After Steps S16 to S24 are executed, in Step S26', simple
F/B control is performed in place of the aforesaid Ne-F/B control
of FIG. 4.
[0116] More specifically, in the case of shift-up, the auxiliary
brake is turned on in Step S26', and it is determined in Step S27'
whether or not the engine revolution speed Ne is within a
revolution speed range such that it is higher than the target Ne
for a gear stage after the gear shift by a predetermined value N3
(Ne.ltoreq.target Ne+N3). If the decision is negative (No), the
engine revolution speed Ne can be concluded to be too high. In this
case, the program returns via Step S29' to Step S26', in which the
auxiliary brake is kept on, i.e. the exhaust brake 52 is closed so
that the engine revolution speed Ne continues to lower.
[0117] If the decision in Step S27' or Step S29' is positive (Yes),
on the other hand, it is concluded that the engine revolution speed
Ne is within the revolution speed range in which it is higher than
the target Ne for the gear stage after the gear shift by the
predetermined value N3 and that the engine revolution speed Ne is
substantially synchronous with the target Ne for the gear stage
after the gear shift. Thereupon, the auxiliary brake is turned off,
and the program proceeds to Step S30 and the subsequent steps of
FIG. 3.
[0118] According to the transmission control apparatus for the
mechanical transmission according to the present invention, as
described above, the engine torque Te is obtained from the
aforesaid equation (5) so that the value of the clutch torque Tcl
of the clutch 3 is 0 (zero) or near 0, and the gears are disengaged
under the engine torque Te without connecting or disconnecting the
clutch unit 3. Thus, the gear shift time can be shortened so that
the gear shift can be quickly achieved without undergoing a shock
attributed to gear disengagement.
[0119] After the gear disengagement, moreover, the gears are
engaged with the engine revolution speed Ne substantially
synchronous with the target Ne for the gear stage after the gear
shift, and therefore, the gear engagement can be carried out
smoothly without connecting or disconnecting the clutch unit 3.
[0120] If the engine torque Te is not obtained correctly from the
equation (5) or if the rack position sensor 9 is out of order, the
clutch unit 3 is disconnected for the gear shift as usual, whereby
the gear disengagement and gear engagement can be performed
securely.
[0121] In the embodiments described above, the clutchless shift
control is performed in response to the gear shift command for the
automatic gear shift mode. Alternatively, however, the clutchless
shift control may be performed in response to a gear shift command
that is outputted in accordance with the driver's gear shift
operation, for example. If clutch pedal operation is carried out by
the driver, in this case, the clutch should only be connected and
disconnected with the pedal operation performed with priority.
[0122] According to the foregoing embodiments, moreover, the diesel
engine is used as an engine type, and the fuel injection quantity
is controlled by the fuel injection pump 6 for use as control means
for the engine torque Te and the engine revolution speed Ne.
Alternatively, however, the engine type may be a gasoline engine,
for example, and the engine may be configured so that the engine
torque Te and the engine revolution speed Ne can be controlled by
adjusting the air intake rate, quantity of fuel injection by a fuel
injection valve, ignition timing, etc.
* * * * *